Room temperature H2S sensor based on Au modified ZnO nanowires

A room temperature H2S sensor based on pure and Au modified ZnO nanowires has been demonstrated. Modification of ZnO nanowires with Au resulted in a remarkable 16-fold increase in the sensor response over pure ZnO NWs toward 5 ppm H2S at room temperature. A sensing mechanism based on the formation of nano-Schottky type barrier junction at the interface between Au and ZnO has been proposed. The enhanced response is attributed to the alteration of barrier properties by the adsorption or desorption of adsorbed species and/or H2S gas molecules. Observance of higher resistivity and a higher work function (0.2 eV) for Au modified samples further corroborates the finding. Low temperature resistivity measurements indicate that the charge transport is governed by the thermal conduction and the nearest neighbor hopping mechanism.